1. Field of the Invention
The present invention concerns an ultra miniature integrated cardiac pacemaker and distributed cardiac pacing system. The invention provides an ultra miniature integrated cardiac pacemaker and distributed cardiac pacing system that allows pacing of the heart without the need for conventional lead wires that connect the electrodes and the main body of the pacemaker, and allows implantation by catheter manipulation without incising the chest wall, which avoids imposing an extra burden on the user.
In this invention, “ultra miniature” refers to the minute size of the pacemaker to the extent that it can be attached to the tip of a catheter.
2. Description of Related Art
A cardiac pacemaker is a device that controls the rhythm of the heart by delivering electrical impulses to the heart, and is indicated for use in patients with symptoms of bradyarrhythmia.
A conventional cardiac pacemaker includes the main body of the cardiac pacemaker (generator), lead wires, and electrodes that transmit a stimulating pulse to the myocardium. The main body of the cardiac pacemaker and the electrodes are connected by lead wires. However, conventional pacemakers have the following problems.
Since the main body of the cardiac pacemaker and the electrodes are connected by lead wires, cases of breaking of the lead wires have occurred. Breakage of the lead wires results in defective pacing. In addition, there have been also cases of venous obstruction by the lead wires.
Moreover, during the early stages after implantation of the cardiac pacemaker, a shift in position of the electrodes may cause defective pacing. When a shift in position of the electrodes occurs, a second operation has to be performed, which adds extra strain for the patient.
Furthermore, if there is a defective hermetic sealing structure at the junction between the cardiac pacemaker main body and the lead wires, this may lead to defective pacemaker movement. Problems with electrical safety have also occurred.
In the Unexamined Japanese Patent Publication Heisei No. 5-245215, a cardiac pacemaker is described in which the signals for cardiac stimulation are delivered from the cardiac pacemaker main body to the stimulation electrodes by wireless transmission, thus eliminating the lead wires between the cardiac pacemaker main body and the electrodes.
However, even for this type of cardiac pacemaker, surgical implantation of the pacemaker cannot be avoided, and there have been cases in which skin necrosis occurred at the cardiac pacemaker implantation site.
Also, in the above-mentioned cardiac pacemaker, although wireless communication is conducted between the pacemaker main body and the electrodes, there is no communication between the electrodes. Synchrony between the multiple electrodes being used is controlled by the pacemaker main body.
The present invention was developed in order to solve the above problems, and to provide an ultra miniature integrated cardiac pacemaker and distributed cardiac pacing system with the following features: the generator function of electric stimulus by the pacemaker main body is integrated with the electrodes, thus allowing pacing of the heart without the need for conventional lead wires connecting the electrodes and pacemaker main body. By integrating the control unit of the pacemaker main body and the electrodes, there is no need to implant the pacemaker main body, which avoids imposing an extra burden on the user.